>The walkman style minidisc recorders get
>considerable time out of AA batteries. They also are somewhat more
>immune to the humidity than cassette.
Walter, in the MD recording system, does the head contact the disc,
as in floppies, or ride on an air cushion, as in hard drives?
-Dan Dugan
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>From Tue Mar 8 18:22:36 2005
Message: 2
Date: Fri, 09 Aug 2002 14:16:53 +0200
From: Klas Strandberg <>
Subject: Re: input transformers (was: Re: mic pre with headphone out)
When you balance electronically you need two preamps, -one inverting and one
non-inverting. With a balancing transformer you only need one amp.
I'm talking about all those 5 and 10 mm electret capsules that you can buy
for a dollar or two. Some of them are very good, you know, if noise isn't
important. Sennheiser has a noisy 5 mm electret for 10 dollars which is as
flat as your Ivie. Knowles has a 10 dollar rectangular capsule which you can
use for bat's, as it goes well above 60kHz, etc.
But the FET inside those capsules need a 10-20 kOhm resistor, for lowest
noise. The output impedance will be the same as the resistor.
Looking at ready-made electrets on the market, you will find all kinds -
from high output impedance ones, to mic's with a 50c output transformer.
Klas.
At 17:46 2002-08-08 -0700, you wrote:
>>Yes, a transformer helps saving a few mA from the batteries.
>
>That wasn't an advantage I was aware of. How?
>
>> A disadvantage
>>is that you can't connect a "raw" simple electret to most transformers,
>>without a buffer stage. The input impedance is too low.
>
>I thought all electret mikes included a buffer amp. What mikes are
>you talking about?
>
>-Dan
>
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